Nursing home patients treated with antibiotics will be enrolled into this project within 72 hours of initiating antimicrobial therapy. Subjects will be randomized to treatment with either bismuth subsalicylate 30 ml every 6 hours for 21 hours, aspirin 325 mg every 8 hours for 21 days, or placebo 1 tablet every 8 hours for 21 days. Stool will be collected at 0, 7, 14, and 30 days, and assayed for alpha-1 antitrypsin, a marker of protein- losing enteropathy. Blood will be collected at 0, 7, 14, and 21 days, and assayed for serum cytokines, e.g., TNF, IL-2, IL-6, etc.